Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering.

In this study, nanostructured ceria (CeO 2 ) films are deposited on Si(100) and ITO coated glass substrates by pulsed DC magnetron sputtering using a CeO 2 target. The influence on the films of using various gas ambients, such as a high purity Ar and a gas mixture of high purity Ar and O 2 , in the sputtering chamber during deposition are studied. The film compositions are studied using XPS and SIMS. These spectra show a phase transition from cubic CeO 2 to hexagonal Ce 2 O 3 due to the sputtering process. This is related to the transformation of Ce 4+ to Ce 3+ and indicates a chemically reduced state of CeO 2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that films deposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films deposited in the presence of O 2 . CV results specifically show a linear variation with scan rate of the anodic peak currents for both films and the double layer capacitance values for films deposited in Ar/O 2 mixed and Ar atmosphere are (1.6 ± 0.2) × 10 −4 F and (4.3 ± 0.5) × 10 −4 F, respectively. Also, TGA data shows that Ar sputtered samples have a tendency to greater oxygen losses upon reduction compared to the films sputtered in an Ar/O 2 mixed atmosphere. [ABSTRACT FROM AUTHOR]